Abstract: A power supply device includes a first switching element, a second switching element, a transformer having a primary coil, a low-pass filter including an input port connected to the secondary coil, an output terminal connected to an output port of the low-pass filter, a detector for outputting a voltage that follows a voltage at the output terminal, a reference signal generator for generating a reference voltage, a comparator unit for outputting a signal based on a result of comparison between the voltage supplied from the detector and the reference voltage, and an operation pause circuit controlling the first and second switching elements. The operation pause circuit is operable to drive the first and second switching elements according to the signal output from the comparator unit, and to cause the first and second switching elements not to conduct regardless of the signal output from the comparator unit.

Abstract: A power source device includes an input terminal, a first switching element connected to the input terminal, a second switching element connected to the first switching element, a transformer having a primary coil connected to a connecting node between the first and second switching elements, a low-pass filter including a series body of a coil and a capacitor connected to a secondary coil of the transformer, an output terminal connected to a connecting node between the coil and the capacitor, a comparator having a first input terminal connected to the output terminal, and an alternating signal generator connected to a second terminal of the comparator. An output terminal of the comparator is connected to each control terminal of the first switching element and the second switching element via the temporary amplitude generation permissible section.

Abstract: A power source device includes an input terminal, a first switching element connected to the input terminal, a second switching element connected to the first switching element, a transformer having a primary coil connected to a connecting node between the first and second switching elements, a low-pass filter including a series body of a coil and a capacitor connected to a secondary coil of the transformer, an output terminal connected to a connecting node between the coil and the capacitor, a comparator having a first input terminal connected to the output terminal, and an alternating signal generator connected to a second terminal of the comparator. An output terminal of the comparator is connected to each control terminal of the first switching element and the second switching element via the temporary amplitude generation permissible section.

Abstract: A power supply device includes a first switching element, a second switching element, a transformer having a primary coil, a low-pass filter including an input port connected to the secondary coil, an output terminal connected to an output port of the low-pass filter, a detector for outputting a voltage that follows a voltage at the output terminal, a reference signal generator for generating a reference voltage, a comparator unit for outputting a signal based on a result of comparison between the voltage supplied from the detector and the reference voltage, and an operation pause circuit controlling the first and second switching elements. The operation pause circuit is operable to drive the first and second switching elements according to the signal output from the comparator unit, and to cause the first and second switching elements not to conduct regardless of the signal output from the comparator unit.

Abstract: A power source device includes a transformer having a first winding and a second winding, an oscillator self-oscillating with using the first winding of the transformer and supplying an oscillating voltage to the first winding, a rectifier for converting an AC voltage output from the second winding into a DC voltage and outputting the DC voltage, first and second output terminals for outputting the DC voltage output from the rectifier, and a diode connected between the first and second output terminals of the rectifier so that a polarity of the diode is reverse to a polarity of the DC voltage. The first and second output terminals are connected with a load charged with an electric charge having a polarity reverse to the polarity of the DC voltage. This power source device can start operating easily without a Zener diode having a high Zener voltage.

Abstract: In a power supply apparatus having voltage doubler rectifier circuit (5) connected to secondary winding (1B) of transformer (1), diode (13) is connected between transistor (3) and primary winding (1A) of transformer (1). By detecting an AC voltage at a junction point between primary winding (1A) of transformer (1) and diode (13) thereby performing over-voltage protection, the difference between the maximum operating voltage and the no-load operating voltage is decreased and the voltage during no-load operation is lowered and thus small-sized power supply apparatus and peripheral equipment can be provided.

Abstract: In a power supply apparatus having voltage doubler rectifier circuit (5) connected to secondary winding (1B) of transformer (1), diode (13) is connected between transistor (3) and primary winding (1A) of transformer (1). By detecting an AC voltage at a junction point between primary winding (1A) of transformer (1) and diode (13) thereby performing over-voltage protection, the difference between the maximum operating voltage and the no-load operating voltage is decreased and the voltage during no-load operation is lowered and thus small-sized power supply apparatus and peripheral equipment can be provided.